Field of the Invention and Related Art
The present invention relates to a guanidine type compound for developing electrostatic images and a toner having the guanidine compound. The present invention also relates to a developer containing the toner for developing electrostatic images. The present invention further relates to an apparatus unit which is detachably provided on the apparatus body and which comprises a developing means having the toner or the developer for developing electrostatic images and a body to be charged, both of which are integrally supported to form the unit. The present invention still further relates to an electrophotographic apparatus having a developing means, which holds the toner or the developer for developing electrostatic images, and to a facsimile apparatus which uses as a printer the electrophotographic apparatus.
Various electrophotographic methods have been disclosed in, for example, U.S. Pat. No. 2,297,691 and Japanese Patent Publication Nos. 42-23910 and 43-24748.
The developing methods applied to the electrophotographic methods are roughly classified into a dry developing method and a wet developing method. The dry developing method is further divided into a method using a two-component developer and a method using a one-component developer.
Fine powder of natural or synthetic resins in which a dye or pigment is dispersed is used as a toner applied to the dry developing method. For example, particles having sizes ranging from 1 to 30 .mu.m, which are obtained by pulverizing a binder resin such as polystyrene in which a coloring agent is dispersed, are used as the toner which is used as the one-component developer. Particles containing a magnetic material such as magnetite are used as a generally known magnetic toner. In the case of the method using a two-component developer, the toner used is generally mixed with carrier particles such as glass beads or iron powder.
Both of the above toners must have positive or negative charges corresponding to the polarity of the electrostatic latent image developed.
While the resin component of the toner itself may be charged by frictional electrification, the resins normally used only frictionally electrify to a relatively low level. This results in impeded development with unclear and fogged images. In order to frictionally charge the toner particles to a desired level, a charge applying agent, called a charge controlling agent, is added to the toner.
Examples of charge controlling agents, which are presently known as agents having the property of being positively frictionally charged, include nigrosine dyes, azine dyes, triphenylmethane dyes and pigments, quaternary ammonium salts and polymers having quaternary ammonium salts in side chains thereof.
Since such charge controlling agents easily soil a sleeve or carriers, however, the frictional charge amount of the toner, which contains one of the controlling agents, decreases with an increase in number of the sheets of copying paper used. This causes a decrease in image density.
Since a certain kind of charge controlling agent has the insufficient property of being frictionally charged and is easily affected by temperature and humidity, the agent causes the image density to be changed by an environmental change. In addition, since a certain kind of charge controlling agent has poor dispersibility in resins, the toner containing this agent produces nonuniformity in the frictional charge amount of the toner particles and easily produces fogging. Further, since a certain kind of charge controlling agent has poor preservative stability, the ability to have frictional charges deteriorates during preservation for a long time. A certain kind of charge controlling agent is colored and thus cannot be used in color toners.
In the present situation, therefore, there is a great demand for a charge controlling agent, which removes the above-described problems, and thus such an agent has been developed.